2.8 - Do I still need to mark each animation action for saving?
So, did a little extra checking on the Blender Artists forums and it seems that, for the moment at least, Fake User is still required.

thedaemon:


  I’m still going to turn on Fake User because of the loss of animations
  before they fixed it. I don’t honestly know, I ran a test and it seems
  to save, but that was a quick test.


zeauro:


  Actions saving requires a user. If action is used by an animated
  object when Save operator is called : action is saved. If action is
  removed from object that is no more animated when Save operator is
  called, it appears with a 0 next to its name in actions list : action
  will be lost. If action has a fake user, you pressed shield icon
  before removing it from object that is no more animated when Save
  operator is called, it appears with an F next to its name in actions
  list : action is saved.